# Central Tendency

Measures of central tendency are ways of dealing with large sets of data and coming up with an amount to represent a typical piece of data from the set. The most common ways to measure central tendency are mean, median and mode.

**Mean**

The mean, or average, of a set of values is found by adding them up and dividing by the number of values in the set. For example, if you wanted to order a pizza and had a lot of spare time on your hands, you could call around to all the pizza places in town and get the price of a large pizza and put them in a list like this: (in dollars) 14, 12, 15, 13, 10. Now, if you wanted to know the mean price of a pizza, add those amounts up and divide by 5: 14 + 12 + 15 + 13 + 10 = 64; 64 ÷ 5 = 12.8 or $12.80

**Median **

The median price of a pizza would be the middle price if you put them in order. Let’s order the pizza prices above: 10, 12, 13, 14, 15. The middle value is 13, so that would be the median. I just remembered another pizza place that sells its pies for $10. Now our list is 10, 10, 12, 13, 14, 15. If you want to find the median of a list of values that is even, find the mean or halfway point between the two middle values. Here, they are 12 and 13, so halfway between them would be $12.50. Median is used most commonly when a few values are outliers that would skew the mean in one direction. They are used often when talking about things like salaries and home prices because a few very rich people can make the mean higher than most people’s salary or home price. Therefore, median is a more accurate way of showing a typical salary or home price.

**Mode**

The mode is the value that appears most often in a list. In our list of pizza prices just above, 10 is the mode because it appears twice. Our original list of numbers had no mode because no values repeated.

**Range**

Range is the difference between the largest and the smallest number in a set of values. In our set of pizza prices, the largest is 15 and the smallest is 10, so the range is 5 (15 – 10).